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Activity: In Cold Blood

NGSS Science and Engineering Practices:

NGSS Crosscutting Concepts:

NGSS Disciplinary Core Ideas:

Materials

  • Six thermometers or digital temperature probe sensors
  • Six aluminum foil packets
  • Stopwatch
  • Colored construction paper
  • Scissors
  • Tape
  • Rubber bands
  • Water
  • Graph paper

Procedure

A. Hypothesis Testing

  1. Using an aluminum foil packet and thermometer to simulate an individual reptile body, design a set of experiments to test the following three research questions:
    1. What effect does habitat or substrate material have on reptile body temperatures over time? For example, do lizards warm faster on rocks or on grass?
    2. What effect does skin color have on reptile body temperatures over time?
    3. What effect does sunlight intensity have on reptile body temperatures over time?
       
  2. Write out your group’s experimental design, listing materials and procedures. Develop a hypothesis for each research question. Ensure that your experiments are specifically designed to address each hypothesis and research question. Assign specific roles and tasks to each group member.
     
  3. Begin your experiments. If you notice problems with your experiments, discuss them with your group. Consider modifying your experimental design before continuing.
     
  4. Record all collected data in a table. Plot your data in a separate graph for each experiment. Select the type of graph that will present your data most accurately.
     
  5. Analyze your data. Answer questions 1–4 below.

B. Simulating Reptile Behavior: Part I

  1. Reptiles in the real world regulate their body temperatures by using a combination of behaviors. They warm and cool themselves in an attempt to maintain body temperatures within some optimal range where internal chemical processes (e.g., metabolism or processing of food and body wastes) are most efficient. In Part A of this activity, you simulated a variety of different reptile behaviors to determine their effects on body temperatures.
     
  2. Use your findings from Part A of this activity to plan a single combination of behaviors that will produce a target body temperature of 25 °C after 10 minutes.
     
  3. Record the combination of behaviors your model reptile will use: substrate type, skin color, and sunlight intensity.
  4. Using the same foil packet and thermometer apparatus from Part A, begin your simulation and record temperature readings every 30 seconds until reaching 10 minutes total time.
     
  5. Plot your temperature and time data on a graph.

C. Simulating Reptile Behavior: Part II (optional).

  1. Consider the behavior of reptiles in the real world. Reptiles can move in and out of shade and rest on a wide variety of substrates. Some species of reptiles can change their skin color at will. Examples of color-changing reptiles include chameleons, anoles, and some snake species.
    1. Use a combination of reptile behaviors to produce a body temperature that is closest to a fictitious optimal operating temperature for our aluminum foil packet reptile model: 25 °C.
    2. Modify behavior to maintain this ideal temperature for as long as possible throughout the exercise.
       
  2. Record temperature readings from your simulated reptile model for every 30 seconds for 10 minutes. Add notes on the reptile behavior employed during each time 30-second time interval.
     
  3. Plot temperature data on graph paper. Draw a smoother line between data points.
     
  4. Using the smoother line on the graph, estimate the number of minutes the temperature is 25 ± 1 °C. This time within the reptile’s optimal temperature range represents the amount of time it can complete other behaviors such as hunting, courtship, mating, territorial defense, migration, and predator avoidance. Compare your findings with those of other groups in the class.

 

Activity Questions: 
  1. Why do living organisms need to control their body temperatures?
     
  2. Summarize your research findings in two sentences or less for each research question.
    1. How did these findings compare to your hypotheses?
    2. Did the experiments sufficiently address the research questions?
    3. What conclusions, if any, can you draw about behavioral thermoregulation in reptiles?
       
  3. Data representation and communication
    1. Why did you select your particular graphing method to clearly communicate the data?
    2. What are some alternative methods and why are they less suitable for your data?
       
  4. Critique your own research.
    1. What are some limitations with your experimental designs?
    2. How might your experiments be improved in the future? 
       
  5. In Part B of this activity, you were asked to employ a combination of behaviors to achieve a target body temperature in your model reptile.
    1. What behaviors did you select?
    2. How close did you come to achieving the optimal body temperature?
    3. How long did your model reptile stay within 2 °C of this optimal temperature?
    4. How would you modify the reptile behavior if you could try Part B a second time?
       
  6. In Part C of this activity, what combinations of methods produced the most consistent temperatures within the fictitious optimal temperature range?
     
  7. What are some of the evolutionary advantages of skin color changing in reptiles? Can you think of any advantages aside from regulating body temperatures?
     
  8. A dog is an example of a mammal. All mammals are endotherms, in contrast to ectotherms like reptiles. A healthy dog’s internal body temperature is typically around 38 °C. What would a dog’s internal temperature be on a cold winter day with air temperatures near 0 °C? Why?
     
  9. Aquatic reptiles—particularly marine reptiles—face a unique set of challenges regarding thermoregulation.
    1. a. How do different groups of marine reptiles modify their behavior to regulate internal body temperatures?
    2. b. How might you simulate marine reptile thermoregulation in a model experiment?
       
  10. Why are most reptiles active during the day? How are some reptiles capable of living nocturnal lifestyles, such as most gecko species?

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Exploring Our Fluid Earth, a product of the Curriculum Research & Development Group (CRDG), College of Education. University of Hawaii, 2011. This document may be freely reproduced and distributed for non-profit educational purposes.